Questions and Answers
What is the UL, LLC requirement for ground-fault circuit interrupters regarding tripping?
Which of the following are common shock severity factors for humans? (Select all that apply)
What is a device intended for the protection of personnel that functions to deenergize a circuit when a current to ground exceeds the values established for a Class A device?
Ground-fault circuit interrupter
Ground-fault circuit interrupter protection is available in which types of equipment or products? (Select all that apply)
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What is the operating imbalance threshold that a ground-fault circuit interrupter operates on?
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Ground-fault circuit-interrupter protection is required for receptacles installed within how many feet of a sink in a dwelling unit? (Select all that apply)
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In older existing installations without equipment grounding conductors at the outlets, which is acceptable for receptacle replacements? (Select all that apply)
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What provides a method for installing an equipment grounding conductor for receptacles that are being replaced at a location where one is desired but is not present?
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Where installed in dwelling unit kitchens, all 125-volt, single-phase, 15- and 20-ampere receptacles that are installed to serve what shall be GFCI protected? (Select all that apply)
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What contains the requirements for ground-fault protection for personnel using temporary power?
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What is generally required for grounded electrical services and feeders of more than 150 volts to ground but not exceeding 1,000 volts phase-to-phase?
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What is defined as a system intended to provide protection of equipment from damaging line-to-ground fault currents?
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What does Section 230.95 require regarding ground-fault protection?
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What is the maximum setting for ground-fault protection of equipment?
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What voltage and phase arrangement requires ground-fault protection of equipment?
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To whom is a record of performance testing of ground-fault protection required to be made?
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In health care facility power systems, the additional level of GFPE is not permitted on the load side of what?
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What does a zero-sequence-type GFPE typically consist of?
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What is the maximum time-delay for ground-fault currents that exceed 3,000 amperes?
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Which sections require ground-fault protection of equipment to be performance tested when first installed on site? (Select all that apply)
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What is one significant difference between ground-fault circuit interrupters and ground-fault protection of equipment?
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Which of the following is not a requirement of the NEC for GFPE installed in service equipment as part of a new construction project?
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In wet procedure locations of health care facilities, which type of protective equipment is required when GFCI protection cannot be installed?
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Study Notes
Ground-Fault Circuit Interrupters (GFCI)
- Class A GFCIs trip when continuous 60-hertz differential current exceeds 6 mA and do not trip below 4 mA.
- Common shock severity factors for humans include the amount of current, frequency, duration, body path, and person size.
- GFCIs protect personnel by de-energizing circuits when current to ground exceeds specified Class A values.
- GFCI protection is available in circuit breakers, cord sets, outlet devices, and plug-in adaptors.
GFCI Operation and Installation
- GFCIs monitor supply and return current conductors for imbalances exceeding 4 to 6 mA.
- GFCI protection is required for receptacles within 3, 5, or 6 feet of sinks in dwelling units.
- Existing installations can replace non-grounding receptacles with GFCI devices, marked "No Equipment Ground," or replace with grounding-type receptacles through GFCI devices, marked accordingly.
Equipment Grounding Conductors
- Section 250.130(C) allows for installing grounding conductors where none exist during receptacle replacements.
- GFCI protection is mandated for receptacles serving countertop surfaces or within 6 feet of sink edges in kitchens.
Regulations and Standards
- NEC 590.6 details ground-fault protection requirements for temporary power at construction sites.
- Ground-fault protection of equipment is required for grounded electrical services over 150 volts to ground, not exceeding 1,000 volts phase-to-phase.
- Service disconnects rated 1,000 A or more must comply with Section 230.95, requiring ground-fault protection.
Technical Specifications
- Maximum setting for ground-fault protection of equipment is 1,200 A, with a one-second delay for currents over 3,000 A.
- Voltage systems requiring protection include 480Y/277V, 3-phase, 4-wire, wye-connected configurations.
- Performance testing of ground-fault protection equipment is mandatory upon installation, with records kept for the authority having jurisdiction.
Additional Context
- Health care facilities must not place additional ground-fault protection on the load side of essential system transfer switches.
- Neutral-ground strap type systems monitor ground-fault currents at the main bonding jumper.
- Zero-sequence-type protection components include a current sensor around all conductors, a ground-fault relay, and a shunt-trip circuit breaker.
Key Differences Between GFCI and GFPE
- GFCIs focus on providing protection to individuals, while ground-fault protection of equipment safeguards electrical devices.
- Performance testing, while necessary for GFPE upon installation, can utilize push-button testing rather than primary injection testing as per NEC requirements.
Special Requirements in Healthcare
- In critical areas where GFCIs cannot interrupt power, isolated power systems are mandated for patient safety, as specified in section 517.160.
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Description
Test your knowledge on Ground-Fault Circuit Interrupters (GFCI) and Ground-Fault Protection of Equipment (GFPE) through this set of flashcards. This lesson covers critical aspects like tripping requirements and shock severity factors relevant to electrical safety.